hadoop SerializationFactory 源码
haddop SerializationFactory 代码
文件路径:/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/serializer/SerializationFactory.java
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.io.serializer;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.CommonConfigurationKeys;
import org.apache.hadoop.io.serializer.avro.AvroReflectSerialization;
import org.apache.hadoop.io.serializer.avro.AvroSpecificSerialization;
import org.apache.hadoop.util.ReflectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <p>
* A factory for {@link Serialization}s.
* </p>
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Evolving
public class SerializationFactory extends Configured {
static final Logger LOG =
LoggerFactory.getLogger(SerializationFactory.class.getName());
private List<Serialization<?>> serializations = new ArrayList<Serialization<?>>();
/**
* <p>
* Serializations are found by reading the <code>io.serializations</code>
* property from <code>conf</code>, which is a comma-delimited list of
* classnames.
* </p>
*
* @param conf configuration.
*/
public SerializationFactory(Configuration conf) {
super(conf);
for (String serializerName : conf.getTrimmedStrings(
CommonConfigurationKeys.IO_SERIALIZATIONS_KEY,
new String[]{WritableSerialization.class.getName(),
AvroSpecificSerialization.class.getName(),
AvroReflectSerialization.class.getName()})) {
add(conf, serializerName);
}
}
@SuppressWarnings("unchecked")
private void add(Configuration conf, String serializationName) {
try {
Class<? extends Serialization> serializionClass =
(Class<? extends Serialization>) conf.getClassByName(serializationName);
serializations.add((Serialization)
ReflectionUtils.newInstance(serializionClass, getConf()));
} catch (ClassNotFoundException e) {
LOG.warn("Serialization class not found: ", e);
}
}
public <T> Serializer<T> getSerializer(Class<T> c) {
Serialization<T> serializer = getSerialization(c);
if (serializer != null) {
return serializer.getSerializer(c);
}
return null;
}
public <T> Deserializer<T> getDeserializer(Class<T> c) {
Serialization<T> serializer = getSerialization(c);
if (serializer != null) {
return serializer.getDeserializer(c);
}
return null;
}
@SuppressWarnings("unchecked")
public <T> Serialization<T> getSerialization(Class<T> c) {
for (Serialization serialization : serializations) {
if (serialization.accept(c)) {
return (Serialization<T>) serialization;
}
}
return null;
}
}
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